Hair is composed of keratin, a sulfur-containing fibrous protein. The isoelectric point of keratin, and more specifically of hair, is generally in the pH range of 3.2–4.0. Therefore, at the pH of a typical shampoo (about 5.5–6.5), hair carries a net negative charge.
Functional products for hair that provide cleaning and/or additional cosmetic effects after application and rinsing, such as softness, flexibility, good disentangling, a sheen effect and/or a styling effect, have been sought in recent years in the field of hair products.
Amphoteric polymers have been disclosed that provide wet conditioning properties. Many disclosures of amphoteric polymers have been made for a variety of applications and uses. For example, U.S. Pat. Nos. 4,402,977 and 4,996,059 disclose compositions used in the treatment of keratin substances which contain at least one amphoteric polymer.